1887

Microbiology Society logo - Volume 140, Issue 10, 1994

Volume 140, Issue 10

Volume 140, Issue 10, 1994

  • Systematics

    • Permeabilization of mycolic-acid-containing actinomycetes for hybridization with fluorescently labelled oligonucleotide probes

      https://doi.org/10.1099/00221287-140-10-2859

      The application of whole-cell hybridization using labelled oligonucleotide probes in microbial systematics and ecology is limited by difficulties in permeabilizing many Gram-positive organisms. In this investigation paraformaldehyde treatment, acid methanolysis and acid hydrolysis were evaluated as a means of permeabilizing mycolic-acid-containing actinomycetes prior to hybridization with a fluorescently labelled oligonucleotide probe designed to bind to a conserved sequence of bacterial 16S rRNA. Methods were evaluated on stationary-phase cultures of and , none of which could be probed following 4% (w/v) paraformaldehyde fixation. For comparison and to test the general applicability of mild acid pretreatments, and were also studied. The data showed that most of the mycolic-acid-containing organisms were successfully permeabilized by mild acid hydrolysis in 1 M HCl at 37°C. Cells were treated for different lengths of time. In general, the mycolic-acid-containing organisms required between 30 and 50 min hydrolysis, whereas and were rendered permeable in only 10 min. Interestingly, could not be permeabilized using acid hydrolysis even after 60 min exposure to 1 M HCl.

    • A numerical phenotypic taxonomic study of the genus

      https://doi.org/10.1099/00221287-140-10-2867

      A numerical phenotypic taxonomic study of 315 strains of and some allied bacteria examined for 155 phenotypic tests showed 31 groups, most of which were reasonably distinct. These fell into four major areas. Areas A, B and C contained species of , whereas area D contained the organisms known as ‘false neisserias’ together with and species. Area A contained (which showed two subgroups), (with two subgroups, and closely associated), subsp. and Area B contained mainly organisms from the human nasopharynx, and the nine groups were not very distinct: only three, and could be recognized by the presence of type strains, and there was little relationship between taxonomic position and species epithets. Area C contained several groups from animals, and two phenons that may be justified as new species of , one from lizards and the other from dental plaque of herbivores. Area C also contained (with ), type strain of and the CDC groups M-5 () and EF-4. Area D contained , a combined group which consists of strains of the ‘false neisserias’and , the ‘false neisserias’ , and a group of strains. A small group representing is included in area D. Mean test error was 1.7%.

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  • Genome Analysis

      • Pulsed-field gel electrophoresis analysis of the genome of amino acid producing corynebacteria: chromosome sizes and diversity of restriction patterns

        https://doi.org/10.1099/00221287-140-10-2841

        A large number of species of corynebacteria are known to be amino acid producers, including members of the genera and Pulsed-field gel electrophoresis (PFGE) of DNA fragments obtained by using endonucleases which recognize AT-rich hexanucleotide or octanucleotide sequences produces a discrete pattern of bands useful for fingerprinting and physical mapping of the chromosome. Using and endonucleases the genome of ATCC 13869 (genome size 3052 kb) was consistently cut into 26 and 20 bands, respectively, and the genome of ATCC 13032 (2987 kb) yielded 27 and 26 fragments, respectively. The pattern of restriction fragments was identical for related strains (ATCC 13869, BLO, R31) but different from the pattern of fragments of other soil isolates of the same species (DSM 20412) or from closely related organisms such as ; the different pattern of restriction fragments may be used to differentiate taxonomically related species. showed a different behaviour, due to its high G + C content; its genome (3105 kb) was resolved into 8 or 15 fragments, respectively, by digestion with the hexanucleotide-recognizing endonucleases and PFGE of DNA fragments obtained using these enzymes is a powerful technique for quick resolution of the corynebacteria genome into a small number of large fragments.

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